U.S. patent application claims the priority of PCT International Application No. PCT/JP99/02382, filed on May 07, 1999.
The present invention relates to a middle-sized garbage disposing device that ferments and disposes of organic substance such as leftovers and raw garbage and changes them into compost in a short time efficiently.
Conventionally, a middle-sized garbage disposing device that disposes and changes raw garbage into compost is recognized as the middle size of a small device for a household and a big one for industry that is equipped with a grinding device, a mixing device and a fermentation disposal tank. A typical example of the middle size garbage disposing device is shown in FIG. 3. As indicated, a conventional garbage disposing device 3 comprises a generally cylindrical disposing tank 30 for storing organic substances such as garbage and a fermentation accelerator additive in which fermentation microorganism is seeded beforehand in a sealed condition, a rotating shaft 32 which passes vertically through the disposing tank 30 and is driven to rotate by a motor (not shown) connected to the lower end of the disposing tank, a cylinder 33 having a peripheral wall that is disposed at the upper side of and concentrically around the rotating shaft 32 and has many holes 33a thereon, and a screw blade 34 which is set in a spiral and is disposed on the rotating shaft 32 extending from below to the inside of the cylinder 33.
The method of using this garbage disposing device is as follows. As preparation process, a predetermined amount of the fermentation accelerator additive 35 in which the fermentation microorganism is seeded beforehand is put on bottom of the disposal tank. This additive 35 is made up of bacteria that is cultured from many kinds of microorganism in the soil and small wood chips of wood. Raw garbage (maximum 500 kg) is thrown to the additive from a raw garbage entrance 30a of the disposing tank 30. The motor is driven to rotate the rotating shaft 32 at a speed of 70 rounds/min. The fermentation accelerator additive 35 and the raw garbage are guided in the cylinder 33 by the screw blades 34 fixed on the rotating shaft 32 and are elevated on the inside thereof. Since there are many holes 33a on the cylinder 33, the fermentation accelerator additive and the raw garbage are subjected to cutting so that they are broken into small pieces, are pressed into the holes 33a and fall down on the bottom of the disposing tank 30.
In this way, after they are ground and mixed sufficiently, the motor is stopped and they are left, for example, to ferment for two or three days. During this time period, the raw garbage is resolved into carbonic acid gas and water due to work of bacteria so that good and homogeneous compost is produced.
Considering from the view point of processing efficiency in said raw garbage disposing device 3, it is necessary to grind and mix the fermentation accelerator additive and organic substance sufficiently as well as to process the fermentation disposal equally at the upper, the middle and the lower parts of the disposing tank 30. FIG. 4 represents the temperature change in the lower tank of the disposing tank 30 in case that the raw garbage was thrown into the disposing tank 30 of the conventional garbage disposing device 3 at levels of 40 cm, 55 cm 67 cm height, respectively. (The experiment for each height was done twice.) As a result, it was found that the fermentation disposing progresses rapidly in proportion to the amount of the raw garbage put into the disposing tank 30 as long as the motor rotating the rotating shaft 32 permits. In other words, when the fermentation disposal progressed, the temperature of disposal materials thrown into and ground and then mixed was increasing. As it is shown in FIG. 4, the higher the amount of raw garbage thrown into, the higher the temperature of the fermentation disposal was or the fermentation progressed.
Next, the raw garbage was thrown into the disposing tank at 30 to 65 cm in height, and the change of the temperature in the lower, middle and upper parts of the disposing tank were checked under the same condition as described above (refer to the FIG. 5). As a result, there was more than 10 degrees difference in temperature between the lower and the upper part of the disposing tank 30 during a period from 30 minutes to two hours after the beginning of disposing. Furthermore, there was a drawback that the progress of disposing became slow, in the case of only 5xcx9c6 degree difference in temperature even after 7 hours passed from the beginning of disposing.
The purpose of the present invention is to solve the above drawback of the conventional garbage disposing device and offer a garbage disposing device that is able to perform fermentation disposal at almost the same processing condition at all heights of a disposing tank.
The present invention to solve the above drawback provides a garbage disposing device which comprises a disposing tank having a decreasing radius in a horizontal cross section downwardly for storing an organic substance such as garbage and fermentation accelerator additives in which fermentation microorganism is seeded beforehand in a sealed condition, a rotating shaft which passes vertically through the disposing tank and is driven to rotate by a motor connected to the lower or upper end of the disposing tank, a plurality of cutter blades which are fixed in a cantilevered fashion to the rotating shaft at intervals in the vertical direction for grinding and mixing the fermentation accelerator additive and the organic substance, and a plurality of thermo sensors for detecting the temperature of the disposing tank at a plurality of portions positioned at intervals in the vertical direction.
Grinding and mixing can be performed sufficiently with small rotating resistance at various vertical positions of the disposing tank because the disposing tank is formed to have the decreasing radius in horizontal cross section downwardly and the grinding and mixing is performed by the plurality of cutter blades mounted on the rotating shaft.
The present invention is also characterized in that the disposing tank forms an inverted-conical shape with an inclination to the vertical direction of 20-50 degrees.
With this range of inclination angle, the rotating resistance loaded over the cutter blades becomes small and the device is efficient, because it is supported by the wall that supports a part of the load from the upper part of the raw garbage that is thrown or put into the disposing tank.
The present invention is also characterized in that the height of the disposing tank is 100 cm or less.
To perform grinding and mixing the fermentation accelerator additive and the organic substance sufficiently, the device needs a rotating speed of about 110 rounds/min. With a general-use motor available at low cost, the height of the disposing tank is formed to 100 cm or less to avoid excessive load to the motor.
The present invention is also characterized in that an entrance for the organic substance into the disposing tank is formed on the top and an outlet of disposed compost is formed at the bottom of this disposing tank.
By forming the entrance for the organic substance on the top of the disposing tank, the organic substance can be thrown into the disposing tank easily just by releasing the organic substance above the entrance. By forming the outlet for the disposal compost at the bottom of this disposing tank, all compost can be discharged outside of the disposing tank easily, because it falls down to be gathered toward the bottom of the disposing tank due to the decreasing radius in horizontal cross section downwardly and the inverted conical shape along the slope of the tank.
The present invention is also characterized in that it checks or monitors the temperature of disposing at least in the upper, middle and lower parts of the disposing tank and detects the transitions in the temperature increasing, the temperature staying constant and the temperature decreasing, and re-grinds and re-mixes the material by rotating the motor as needed, discharges the disposed compost from the bottom of the disposing tank, and/or throws or puts new organic substance such as raw garbage into this disposing tank.
The progress of the fermentation disposal can be detected from the temperatures at various positions of the disposing tank and is controlled using the temperatures as parameters to make fermentation disposal throughout the disposing tank homogeneous and efficient.